1. Field of the Invention
The present invention relates to improved reactor iron making. Specifically, the present invention relates to an apparatus for reactor iron making that has a highly rationalized arrangement, and to methods of supplying raw material and utilizing exhaust gas when the apparatus is used for reactor iron making.
2. State of the Art
We have previously established a technique of making iron (meant here to include pig iron and steel) by melting scrap using carbonaceous materials and oxygen, rather than using electric power or coke, and named it "Reactor Iron Making", which was disclosed in Japanese Patent Disclosure No. 57-198206.
With this method not only scrap but also reduced iron can be used as the raw material, and optimum operating conditions in the case of reduced iron have been determined as disclosed in Japanese Patent Application No. 59-35842.
The basic method of "Reactor Iron Making" involves charging the reactor, containing molten iron and an air space above it, with scrap and carbonaceous material, and blowing oxygen through the molten iron to stir it and oxidize the carbonaceous material mainly to CO. Oxygen is also blown into the above-mentioned air space above the molten iron to oxidize CO to CO.sub.2. Heat generated by the oxidation melts the scrap, and the high temperature exhaust gas is utilized for preheating charged scrap.
Through further research the advantages of a method of using the heating of the charged scrap became clear. More than the burning of gas, containing CO, in the air space of the reactor, the gas is extracted to the outside, air is added, and burning takes place, raising the temperature.
In the improved apparatus a scrap preheating shaft is positioned directly above the reactor, and the bottom of the shaft is provided with a damper that is closed during preheating in order to hold the scrap. The damper is opened to allow the scrap to fall directly into the reactor in such a way that charging is ensured regardless of the shape and size of-the scrap. In order to prevent the damper from being damaged by heat, cooling water is passed through the interior, but if exposed to high temperature gas, life of the damper is short. It was effective to alter the waste gas passage to introduce the waste gas at the top of the scrap and remove it at the bottom, that is, so that the waste gas comes into contact with the damper after heating of the scrap when the temperature of the gas has decreased. However, damage to the damper cannot be ignored when it faces the reactor, because both sides absorb heat.
An apparatus for reactor iron making requires that every component inclusive of the above-noted parts be durable and long lasting. Improvement in heat efficiency is also a continual problem, and heat loss must be reduced. A guarantee of airtightness is important. It is necessary to charge the heating shaft with raw material while maintaining an airtight condition because normally high temperature gas is introduced into the heating shaft. It is also necessary to charge the furnace body smoothly with the heated raw material under an airtight condition.
In order to exhibit the advantages of "Reactor Iron Making", it is essential to raise the level of heat utilization even more. Also, loss due to oxidation of the scrap must be avoided at all costs.